Datta et al. U.S. Pat. No. 4,921,767, issued on May 1, 1990, describes a method for electrophotographically manufacturing a luminescent screen assembly on an interior surface of a CRT faceplate using dry-powdered, triboelectrically charged, screen structure materials deposited on a suitably prepared, electrostatically chargeable surface. The chargeable surface, or photoreceptor, comprises an organic photoconductive layer overlying a conductive layer, both of which are deposited, serially, as solutions on the interior surface of the CRT panel.
The conductive layer of the aforementioned patent comprises either an inorganic conductor, such as tin oxide, indium oxide, or a mixture of indium-tin oxide, or, a volatilizable organic conductive material consisting of a polyelectrolyte commercially known as Polybrene, available from Aldrich Chemical Co., Milwaukee, Wis. A drawback of the latter mentioned material is that it possesses high surface resistivity (.gtoreq.10.sup.11 ohms/square) which results in slow and non-uniform charging of the overlying photoconductive layer at low relative humidity (&lt;50% RH). Also, it tends to crack during filming, and is prone to crystallize causing defects in the screen assembly.
A need exists for suitable materials that overcome the above-mentioned shortcomings of the latter mentioned known material and which are inexpensive and compatible with the photoconductive layer.